Artikel
Maturation and proteolytic processing of severe ccute respiratory syndrome (SARS)-associated coronavirus spike protein
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Veröffentlicht: | 26. Mai 2004 |
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Gliederung
Text
The spike protein (S) of severe acute respiratory syndrome associated coronavirus (SARS-CoV), a close relative to coronavirus group 2, is a type I glycoprotein, which forms large spikes on the surface of the virion. The ectodomain of the spike protein is extensively N-glycosylated and is essential for the interaction with host cell receptors and membrane fusion. The protein consists of 1255 amino acids containing 17 potential N-glycosylation sites, a signal peptide and a C-terminal membrane anchor. Some coronavirus spike proteins (MHV, HCoV-OC43, AIBV and BCoV), but not all (TGV, FIPV, HCoV-229E) are proteolytically cleaved in two subunits, S1 and S2, carboxyterminal of a basic amino acid motive recognized by subtilase furin. Whether cleavage is essential for the function of S proteins of all coronaviruses is still under discussion.
In order to investigate the maturation and proteolytic processing of SARS CoV spike, infected or transfected Vero cells, purified virus and in vitro translated S protein were analyzed. Whereas, intracellular spike is predominantly modified by high-mannose-type oligosaccharides virus associated spike protein contains complex-type oligosaccharides. Putative cleavage fragments reflecting the mass of S1 and S2, respectively, were observed by subunit specific antibodies indicating proteolytic processing of the S protein precursor.